ericn
Temp
Balance Engineer
Posts: 14,934
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Post by ericn on Apr 28, 2020 10:35:36 GMT -6
Just curious, John. Have they implemented 5G in your area? Not sure...but I AM growing an arm out of my forehead. That explains a lot! If it’s a right arm, I could sure use the thumb and first finger😎
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Post by chessparov on Apr 29, 2020 1:47:30 GMT -6
Unlike North Korea, this is getting disarming... Chris
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Post by Johnkenn on Oct 27, 2020 15:33:56 GMT -6
drbill Is this what you were talking about?
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Post by Johnkenn on Oct 27, 2020 15:36:47 GMT -6
That's a solid state mic, but wonder if the female end of my XLR going out of the PS could be done this way...I have zero electronical smarts, so someone tell me if doing this to the cable might make something explode. My thought is it might be the actual cable that runs from the 251 casing that screws into the Upton or the other end of it that goes into the PS. That's not a regular XLR
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Post by drbill on Oct 27, 2020 15:42:41 GMT -6
Yeah, that's it exactly. I put out this info up on the internet a decade ago and hundreds of people have done the "mod", which isn't even a "mod" really and had total success with it. It's a cable that terminates the audio ground to the shell of the XLR (chassis ground) vs. Pin 1 of the XLR which (generally) floats and does not connect to the shell of the mic. Not sure how it would shake out with a tube mic. But the "issue" is definitely a ground issue.
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Post by Johnkenn on Oct 27, 2020 16:12:07 GMT -6
I mean - I guess I could just try it and see if the XLR cable into the PS is the issue...doubt it is, though.
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Post by Johnkenn on Oct 27, 2020 16:13:11 GMT -6
Actually, I guess there's no point in that. I don't get the RF with the Heiserman. It's got to be the Upton cable.
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Post by drbill on Oct 27, 2020 16:48:37 GMT -6
I mean - I guess I could just try it and see if the XLR cable into the PS is the issue...doubt it is, though. John - The problem is not the XLR cables. Most gear has both chassis and audio grounds inherent in the design - mics included. Sometimes how the manufacturer treats these two grounds, how they interface with each other, and how the internal circuitry gets grounded gets sketchy under different circumstances and environments. The aforementioned XLR cables are normal, built fine, and good to go in 99 out of 100 applications. The 1 out of 100 is where there is an RF problem. Solving it (for me and many others) entails taking the AUDIO ground on the XLR cable at the mic end (Female XLR), and attaching it to the shell of said XLR - essentially tying the audio ground to the chassis ground of the mic. If you have doubts, or are not understanding things, contact a tech with the information and it should be a simple (and hopefully) easy fix.
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Post by svart on Oct 27, 2020 17:08:26 GMT -6
I'm the RF world, where I work, it's a biiiiig no-no to have separate grounds or to float a ground in any way. To that end I always ground the shell of a connector.
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Post by drbill on Oct 27, 2020 19:41:04 GMT -6
I'm the RF world, where I work, it's a biiiiig no-no to have separate grounds or to float a ground in any way. To that end I always ground the shell of a connector. Aren't all pre made (or for that matter, DIY) XLR mic cables made with pin 1 not attached to the shell svart?
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Post by Ward on Oct 28, 2020 6:57:53 GMT -6
I'm the RF world, where I work, it's a biiiiig no-no to have separate grounds or to float a ground in any way. To that end I always ground the shell of a connector. Aren't all pre made (or for that matter, DIY) XLR mic cables made with pin 1 not attached to the shell svart? I reckon I have about 60-70 star-quad mic cables, and I made all but 10 of them. I always connected the ground/shield to both pin-1 and the housing. I've rarely ever had an RF problem with any cable I've made. That being said, the issue that John (and others here) are pointing out is originating in the XLR-7 cabling being used to make up the cable from the tube microphone to the power supply. This happens WAY too often. Besides the U67 and H47T, one of my favorite tube mics is my Telefunken CU29 copperhead. But the cable it came with? JUNK. I replaced it with a cable that cost 4x what the original is worth and WOW, what an improvement in sound and elimination of interfering noise. I've got to do the same with the U67 as well, because the cable it comes with is junk compared to what I got with the Heiserman H47 and what I bought for the CU29. The original cable that came with my C12a is still perfect after ~60 years, but I don't know why they had to make it ~250 feet long.
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Post by Johnkenn on Oct 28, 2020 7:06:06 GMT -6
I need to open that 7 pin up and take a look. Wish I could find a pin out for it.
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Post by svart on Oct 28, 2020 7:14:31 GMT -6
I'm the RF world, where I work, it's a biiiiig no-no to have separate grounds or to float a ground in any way. To that end I always ground the shell of a connector. Aren't all pre made (or for that matter, DIY) XLR mic cables made with pin 1 not attached to the shell svart? Of the few cables I've bought, a couple did and a couple didn't. Some older xlrs have the connection natively with a small metal finger. A lot of PCB mounted xlr jacks have a separate pin for grounding the shell too.
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Post by svart on Oct 28, 2020 7:15:55 GMT -6
I need to open that 7 pin up and take a look. Wish I could find a pin out for it. Generally speaking, whichever pin the shield braid is going to is the ground pin, however some supplies separate power ground from signal ground, and this is likely where the issue is.
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Post by EmRR on Oct 28, 2020 9:54:00 GMT -6
My understanding is for the last 2-3 decades it’s been recommended to leave xlr 1 and connector body disconnected. Previously it was recommended to connect them, and consensus became that it caused more problems than it solved. You can make the argument that it depends on the type of connection, which says, by all means, try connecting them or disconnecting them if there’s a problem, and see. You can always find a situation that defies usual recommendations. I personally have no XLRs with 1 and connector connected. With a line output or mic/line input 1 and chassis are connected inside the equipment, so the shell gets grounded anyway if it’s a metal panel connector. .
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Post by drbill on Oct 28, 2020 10:17:07 GMT -6
I personally have no XLRs with 1 and connector connected. With a line output or mic/line input 1 and chassis are connected inside the equipment, so the shell gets grounded anyway if it’s a metal panel connector. . 1. Me as well afaik. Studio interconnected XLR's (line level - not mic cables) have pin 1 lifted on one end. (for the most part afaicr - star grounding). 2. I believe this is the problem with the Gefell mics. Poor chassis (mic shell) to audio ground issues. But on SOME mics only. I have 3 consecutive serial numbered M71S;s and the middle serial number is perfect in high RFI environments. The outer two serial numbered mics had the described problem in spades. So weird....
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Post by svart on Oct 29, 2020 13:54:33 GMT -6
I personally have no XLRs with 1 and connector connected. With a line output or mic/line input 1 and chassis are connected inside the equipment, so the shell gets grounded anyway if it’s a metal panel connector. . 1. Me as well afaik. Studio interconnected XLR's (line level - not mic cables) have pin 1 lifted on one end. (for the most part afaicr - star grounding). 2. I believe this is the problem with the Gefell mics. Poor chassis (mic shell) to audio ground issues. But on SOME mics only. I have 3 consecutive serial numbered M71S;s and the middle serial number is perfect in high RFI environments. The outer two serial numbered mics had the described problem in spades. So weird.... Are they nickel coated? The nickel coating tends to tarnish and become high impedance, so it there is only a touch of ground to the body, it might get noisy. Oxides can act like diodes (because it's basically how diodes are made, a man-made oxide layer,etc) and they can demodulate AM through the cable (acts as antenna and capacitor) and the oxide (as a diode) to make a sort of radio.
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Post by drbill on Oct 29, 2020 18:56:12 GMT -6
1. Me as well afaik. Studio interconnected XLR's (line level - not mic cables) have pin 1 lifted on one end. (for the most part afaicr - star grounding). 2. I believe this is the problem with the Gefell mics. Poor chassis (mic shell) to audio ground issues. But on SOME mics only. I have 3 consecutive serial numbered M71S;s and the middle serial number is perfect in high RFI environments. The outer two serial numbered mics had the described problem in spades. So weird.... Are they nickel coated? The nickel coating tends to tarnish and become high impedance, so it there is only a touch of ground to the body, it might get noisy. Oxides can act like diodes (because it's basically how diodes are made, a man-made oxide layer,etc) and they can demodulate AM through the cable (acts as antenna and capacitor) and the oxide (as a diode) to make a sort of radio. Nickel on the mics? I'd guess yes. On the cables, I've got nickel and gold both. But I don't have any RF problems anymore after moving the studio outside of LA. All is happy here....
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Post by Ward on Oct 29, 2020 21:06:00 GMT -6
1. Me as well afaik. Studio interconnected XLR's (line level - not mic cables) have pin 1 lifted on one end. (for the most part afaicr - star grounding). 2. I believe this is the problem with the Gefell mics. Poor chassis (mic shell) to audio ground issues. But on SOME mics only. I have 3 consecutive serial numbered M71S;s and the middle serial number is perfect in high RFI environments. The outer two serial numbered mics had the described problem in spades. So weird.... Are they nickel coated? The nickel coating tends to tarnish and become high impedance, so it there is only a touch of ground to the body, it might get noisy. Oxides can act like diodes (because it's basically how diodes are made, a man-made oxide layer,etc) and they can demodulate AM through the cable (acts as antenna and capacitor) and the oxide (as a diode) to make a sort of radio. I never had a problem with AM stations, but occasionaly I get the classic rock FM stations through the 1976 Marshall JMP.
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Post by Johnkenn on Oct 29, 2020 21:31:50 GMT -6
Are they nickel coated? The nickel coating tends to tarnish and become high impedance, so it there is only a touch of ground to the body, it might get noisy. Oxides can act like diodes (because it's basically how diodes are made, a man-made oxide layer,etc) and they can demodulate AM through the cable (acts as antenna and capacitor) and the oxide (as a diode) to make a sort of radio. I never had a problem with AM stations, but occasionaly I get the classic rock FM stations through the 1976 Marshall JMP. It’s really weird. I get classic rock every time it happens to me too.
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Post by svart on Oct 30, 2020 8:13:25 GMT -6
Are they nickel coated? The nickel coating tends to tarnish and become high impedance, so it there is only a touch of ground to the body, it might get noisy. Oxides can act like diodes (because it's basically how diodes are made, a man-made oxide layer,etc) and they can demodulate AM through the cable (acts as antenna and capacitor) and the oxide (as a diode) to make a sort of radio. Nickel on the mics? I'd guess yes. On the cables, I've got nickel and gold both. But I don't have any RF problems anymore after moving the studio outside of LA. All is happy here.... The gefell nickel plating always tarnished and pitted really fast for some reason is why I asked. Some of the later resissue models seemed to fix this before they went to some other coating on their new mics.
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ericn
Temp
Balance Engineer
Posts: 14,934
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Post by ericn on Oct 30, 2020 17:48:08 GMT -6
I need to open that 7 pin up and take a look. Wish I could find a pin out for it. Shouldn’t need a pin out, the ground is either a conductor without its own separate jacket or green. You need maybe 1/2 in of cable to jumper from the ground pin to the contact for the shell.
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Post by spindrift on Oct 30, 2020 19:44:26 GMT -6
On Microphone (and tube mic) cables, I always terminate Pin1 to the XLR shell on BOTH ends. I have never had an RF problem in a mic. I have SOLVED friend’s RF problems by following this methodology as well. Bad pic attached....and that is just a piece of Cat5 solid-core copper that forms the easy bridge. NOTE: The pic makes it look like the bridge is to another XLR PIN but it is to the silver-colored shell connector on the top. Sorry. Attachments:
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Post by adamjbrass on Oct 31, 2020 7:31:25 GMT -6
In my old apartment I had a lot of RF creep into my mics. One time it was obviously happening from laying the cable onto the mic stand.
After sorting that - and still hearing it creep in - I plugged a 25FT outdoor electrical cord between the PSU and the wall and the RF went away.
Sometimes stupid things fix things. Like replacing a Surge protector. The ground pins were loose. Etc.
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Post by johneppstein on Oct 31, 2020 12:24:39 GMT -6
Actually, I guess there's no point in that. I don't get the RF with the Heiserman. It's got to be the Upton cable. Not necessesarily - The Heiserman may connect the audio and shell grounds together inside the mic.
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